High performance footbed and method of manufacturing same

ABSTRACT

A footbed for use in footwear is provided. The footbed assembly includes a resilient, flexible material (e.g. EVA or PU foam) that extends the entire length of the footbed. a heel plate made from a material that is more rigid (plastic, carbon fiber) than the resilient foam attaches to the flexible material. The shape of the resilient footbed defines a geometry that provides support and comfort to the user by reducing peak pressures, improving cushioning, and enhancing foot support. The resilient foam and heel plate defines the shape of the midfoot R 2  and rearfoot R 1  of the footbed while the resilient flexible foam continues forward to define the shape of the forefoot R 3  region of the footbed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 16/158,395,filed Oct. 12, 2018, entitled “HIGH PERFORMANCE FOOTBED AND METHOD OFMANUFACTURING SAME,” which claims priority to U.S. ProvisionalApplication Ser. No. 62/677,582, filed on May 29, 2018, the contents ofwhich are hereby fully incorporated by reference as if fully set forthherein.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to footbeds used in footwearand used with footwear of all types including casual, dress, work, andathletic footwear. More specifically, the present disclosure relates tofootbeds that provide superior comfort and performance to a largersegment of the population, and methods of manufacturing same.

BACKGROUND OF THE DISCLOSURE

Footbeds (also commonly referred to as sockliners or insoles) are acommon component of many types of footwear with a large variation indesign, shape, materials, cost, and overall quality. Much of thisvariation exists between footwear categories and footwear brands toadapt the design of the footbed into the design of the shoe, theintended consumer (athlete, casual, etc.), and price point of thefootwear product.

Footbeds are a primary source of comfort and function in footwear asthey are in direct contact with the plantar surface of the foot wherehigh loads and pressures are realized. Typically, footbeds are made froma relatively thin (3.0-5.0 mm) layer of foam topped by a thin polyesterfabric (top cover) that is adhered to the foam.

The footbed is often a flat piece of foam that does not providesufficient cushioning, pressure reduction, and support for the foot.Footbeds that are molded only from inexpensive foam will quicklybreakdown and take a compression set. This compression set changes theshape of the footbed and reduces the cushioning capability by as much as75%, thus effecting overall comfort and support for the foot.Additionally, standard insoles provide inferior performance due tovariance in foot shapes and sizes.

SUMMARY OF THE DISCLOSURE

In some examples, a method of manufacturing a foot insert includeschoosing a sample patient population, positioning each patient's foot ina sub-talar neutral position, collecting three-dimensional data of atleast one foot of each patient and placing the scan in a collection ofscans representing the sample patient population, separating thecollection of scans into groupings based on each patient's preferredshoe size, aligning the scans within each grouping by usingcorrespondence point pairs, obtaining contour data from the scans,applying at least one filter to the scans, averaging the scans,obtaining seven representative measurements for each grouping, the sevenrepresentative measurements including forefoot width, rearfoot width,arch height, arch length, heel-to-head of first metatarsal phalangealjoint, heel-to-head of fifth metatarsal phalangeal joint, and footlength, and forming an insole based on the seven representativemeasurements.

BRIEF DESCRIPTION OF THE DISCLOSURE

Various embodiments of the presently disclosed devices and methods areshown herein with reference to the drawings, wherein:

FIG. 1 is an isometric top view of the footbed assembly;

FIG. 2 is an bottom view of the bottom of the footbed assembly;

FIG. 3A-E is a schematic showing the locations of the sevenrepresentative measurements;

FIG. 4 is an illustrative model showing one example of a regressionanalysis;

FIG. 5 is a flow chart showing certain steps in creating a regressionmodel; and

FIG. 6 is a diagram showing certain steps, including optional steps,that may be used in manufacturing an insole.

Various embodiments of the present invention will now be described withreference to the appended drawings. It is to be appreciated that thesedrawings depict only some embodiments of the invention and are thereforenot to be considered limiting of its scope.

DETAILED DESCRIPTION

Despite the various improvements that have been made to footwear andtheir methods of manufacture, conventional devices suffer from someshortcomings as described above.

Footbeds may include a shape in the top surface that attempts to matchthe contours of the foot. These footbeds can be made with more durablematerials such as polyurethane foams and support structures made withcomposite materials such as injected plastics and carbon fiber so thefootbed shape is maintained. Footbeds from corporations such as SpencoMedical Corp. and Superfeet Worldwide are examples.

Higher quality materials may be used to produce such footbeds, includingmaterials that are more durable, stiffer, and shaped to match the foot.It should be understood that using more durable, higher qualitymaterials will reduce the breakdown of materials and maintain thelike-new performance.

However, matching the shape of the plantar foot surface is a complicatedprocess. Footbeds with flat profiles are less effective but can be usedwith the majority of the population of shoe wearers since there is noattempt to match the foot's plantar surface profile. Conversely,footbeds with curvatures that match the foot can be problematic if thespecific geometry of a footbed does not match a particular wearer's footgeometry. A mismatch in this geometry will produce less than idealresults and possibly injury, and can be less effective than footbedswith flat profiles. As can easily be understood, there are billions offoot profiles and shapes within the population. The more specific thefootbed shape, the less likely it is to fit a large segment of thepopulation.

The effort to find a footbed geometry that works for a large populationsegment is a complicated and expensive task. As such, many footwearcompanies charged with designing footbeds do not have the necessaryequipment or the business structure to invest the necessary resources.It is common practice in the footwear industry to produce footbeddesigns from foot data that represents a very small population segmentand hope for the best. While this might solve immediate business needs,the performance of the footbed is often less than ideal.

Therefore, there is a need for further improvements to the devices,systems, and methods of forming footbeds. Among other advantages, thepresent disclosure may address one or more of these needs.

The footbed assemblies for footwear described herein are designed toprovide exceptional comfort and support. The shape and eventual designof the footbed is configured to fit a large segment of the populationand provide comfort and support, particularly in the heel and midfootregions of the foot where comfort and support are most needed.

The dataset of footscans used to derive this optimized formula is amongthe largest ever used and includes more than 120,000 foot scans. Thislarge dataset and the algorithms derived, ensures that the geometry willfit a large segment of the population and the comfort and supportprovided from the geometry will be among the best in the industry.

The footbed assemblies for footwear shown and described herein providesenhanced cushioning, comfort, and support. Additionally, the methods anddesigns provide the above features while fitting into common, productionfootwear without changing the fit of the shoe—a common problem withafter-market footbeds that provide enhanced features by adding morematerial and volume to a footbed.

In some embodiments, a footbed 10 includes a foam layer 20 that runs thelength of the footbed 10 from toe to heel, with a rigid or semi-rigidheel plate 30 attached to the full-length foam 20 and extending from therear part of the footbed 10 to a point in the midfoot R2 as shown inFIGS. 1 and 2. The midfoot R2 point may be proximal to the position offirst and fifth metatarsal heads of the foot. The heel plate 30 has ageometry designed to provide support and comfort to the heel and midfootR2 region of the foot by improving cushioning and reducing pressure onthe plantar foot surface.

The shape resembles the shape of the plantar surface of the foot. Therigidity of the heel plate 30 helps maintain the shape of the geometry.In the forefoot R3 and toe region of the footbed 10 a non-slip material50 is adhered to the lower portion of the full-length foam 20 to addrigidity to the foam to keep the foam from wrinkling during use.Additionally, the non-slip material 50 keeps the footbed 10 fromslipping forward in the shoe by adding friction between the footbed 10and lasting board of the shoe. Ideally, the heel plate 30 includes acutout 80 on the bottom of the heel plate that allows the full-lengthfoam to protrude 70 through the semi-rigid heel plate such that the foamis in contact with the shoe's lasting board providing shock absorption.Additionally, the foam protruding 70 through the heel plate will addfriction between the shoe's lasting board and the footbed 10 providingadditional friction and aid in keeping the footbed 10 from moving duringuse. The protruding foam 70, due to its compliance, also suppliesadditional shock absorption as the foam 70 compresses during loadingprior to the semi-rigid heel plate 30 contacting the lasting board.

Some of the components of a footbed according to this disclosure areshown in FIGS. 1 and 2, and the following nomenclature may be usedthroughout the specification to describe some of these components:

Number Component/Area 10 Footbed 20 Full Length Foam Base 30 Heel Plate40 Midfoot Arch 50 Non-slip forefoot 60 Top Cover 70 Heel Plate FoamProjection 80 Heel Plate Cut Out 90 Heel Cup Wall 100 Height of Arch 110Heel Cup 120 Lateral Heel Cup Wall 130 Medial Heel Cup Wall 140 RearHeel Cup Wall R1 Rearfoot Region of Footbed R2 Midfoot Region of FootbedR3 Forefoot Region of Footbed

Additionally, certain measurements may be used throughout thespecification to describe the footbed including the heel cup depth, heelcup diameter, length to front of heel plate, slope/angle of heel cupwall at medial, lateral, rear side locations, heel plate cutout shape(shown in a guitar pick shape), heel plate foam projection, the distanceprotruding through the guitar pick hole, the arch height, the archspring, and the slope from bottom of heel cup to top of arch.

As used herein the “footbed length” refers to the distance from the backof the heel to the front of the toe, “footbed width” refers to thedistance at the widest point of the forefoot, “heel width” refers to thedistance at the widest point of the heel, “heel plate length” refers tothe distance from the back of the heel plate to the front of the heelplate, “heel plate width at heel” refers to the distance at the widestpoint of the heel plate in heel region, “heel plate width at arch”refers to the width from the medial side of the heel plate to thelateral side of heel plate at the arch, “forefoot thickness” refers tothe thickness of foam in the forefoot region, “heel cup wall height(later, medial, rear)” refers to the perpendicular height distance fromtop of the heel cup wall to the center of the heel, “heel cup wall angle(lateral, medial, rear)” refers to angle of the heel cup wall from thebase of the heel to top of wall, “arch height” refers to theperpendicular height from top of arch to base of heel, and “arch springfrom lasting board” refers to the distance from lasting board to bottomsurface of arch.

The footbed base 20 may be made from a resilient foam material producedwith techniques such as injection or compression molding and made frommaterials such as foamed polyurethane or foamed ethylvinyl acetate(EVA). Additional and less common foams known to the industry such asfoamed rubber or Polyethelene (PE) foam may also be used. The foam istypically of a specific gravity (SG) ranging from 0.15-0.40 with amaterial hardness between 15 & 50 on the asker C scale. These types offoams are common in the footwear industry and known to provide qualitycushioning and comfort characteristics to the wearer. The footbed base20 is of a relatively consistent thickness throughout the footbed 10with thicker sections in the midfoot R2 to accommodate the arch area 40and shaped to match the plantar foot surface. The heel plate 30 is madefrom a material that is more rigid than the foam 20 used for the footbedbase 20 and is commonly made from a plastic material that is producedvia injection or compression molding techniques. Plastics used for theheel plate 30 may include nylon, polyurethane, EVA, polycarbonate, andpeebax. These plastics have a specific gravity in the range of 1.0-1.2and when molded with the above techniques have a hardness of 50-90 onthe shore A scale. Composites such as carbon fiber may also be used withphysical characteristics similar to the plastics mentioned above.

The heel plate 30 is adhered to the bottom surface of the footbed base20 in the heel region R1 and the non-slip material 50 is adhered to thebottom surface of the footbed base 20 in the forefoot R3 region of thefootbed 10. The materials may be adhered to each other using adhesivesknown in the industry or by co-molding the materials via heat andpressure that effectively melts the outer layer of each material to theother.

The heel plate 30 provides the primary shape of the footbed 10 with astiffness and materials that resists long term deformation. The heelplate 30 is attached to the footbed base foam 20 using standardadhesives known in the industry. With the footbed base 20 foam adheredto the heel plate 30, the foam takes the shape of the heel plate 30 andthus has the optimized geometry to match the plantar foot surface. Theheel plate is adhered to and positioned on the footbed base 20 from apoint furthest in the heel to a point in the midfoot R2 that is proximalto the 1^(st) and 5^(th) metatarsal heads of the foot to ensure comfortand compliance at the bending joints of the foot.

The contours of the heel plate 30 that provide the primary shape of thefootbed 10 are critical for comfort and support of the foot. Areaswithin this shape that are significant to the function of the footbed 10include the heel cup depth, heel cup diameter, medial heel cup wallangle, lateral heel cup wall angle, rear heel cup wall angle, medialheel cup wall height, lateral heel cup wall height, rear heel cup wallheight, arch height, and arch spring.

Providing a geometry that closely matches the contours of the foot willprovide needed support and comfort. It will be appreciated that matchingthe contours of the foot will reduce the pressure realized at any givenpoint of the foot. Since pressure=force/surface area and the forceexerted at the junction of the human foot and footbed is a constant foran individual (largely determined by body weight and gait style),increasing contact surface area at a constant force reduces pressure.Thus, matching the contours of the foot is important in reducingpressure. Pressure is a major contributor to comfort as can bedemonstrated by anyone who has stepped on a small object (a pebble) inunshod feet. The force is constant (body weight, gait) but the surfacearea is greatly reduced at the point of contact with the small object.The force (body weight, gait) is now distributed over a small surfacearea (pebble), pressure increases drastically, and discomfort (pain)occurs.

Additionally, support and stability of the foot can be improved via abetter footbed geometry. Supporting critical areas of the plantar footsurface will help control gait, reduce foot pronation, provide archsupport, and improve shock absorption. For example, heel cup wall heightand heel cup wall angle support the sides of the heel and increasestability. A more stable heel will create better stability for the footand lower extremities. The arch profile may also be important forstability as it supports the medial arch of the foot. Better support ofthe medial arch will enhance stability and reduce pronation at theankle. In turn, this will enhance stability throughout the lowerextremity of the body. Those familiar with the kinetic chain in thehuman gait will understand that instability seen at the foot willquickly propagate up the kinetic chain at the other joints of the lowerextremity (ankle, knee, hip), forcing the body to counteract theunstable motion.

In addition to improving overall comfort and support, shock absorptionmay be improved via footbed geometry. In will be appreciated thatincreased contact surface area between the foot and optimized footbed 10allows for greater recruitment of the cushioning material (footbed base20) as more material is used to absorb impact forces of the gait. Ascontact surface area is increased, it effectively incorporates morecushioning material into the shock absorption response.

Additional shock absorption, comfort, and control in in the arch of thefoot is achieved by providing a spring in the arch of the foot. Whencombined with the footbed base 20 the heel plate 30 is molded to a shapethat elevates the bottom surface of the arch area of the heel plate 30from the lasting board of the shoe. This effectively creates a leafspring configuration in the arch area of the footbed 10. As can beappreciated, the leaf spring allows the heel plate 30 and footbed base20 to collapse slightly when force is applied, producing a cushioningeffect as well as allowing the arch to adapt to a specific wearer'sfoot.

Providing a shape that matches the contour of the foot is beneficial tocomfort, support, and cushioning but creates a challenge whenmanufacturing a singular (non-customized) product for a largepopulation. The large variation in shape, size, and profile of theplantar foot surface in a given population means that a shape that mightbe comfortable for one individual will produce discomfort in a secondindividual. Thus, engineering certain predetermined shapes, derived froma large population is desired in the design of a footbed where a singlemanufactured shape is used to create a product that has the greatesteffect for a large percentage of the population.

The shapes of the footbed according to the current disclosure werederived from calculations and algorithms based on a large population of120,000 people. Creating a single product that can be used by a largepopulation of people while providing good performance results benefitsthe users as it reduces the cost of the mass-produced product. Moreover,the production of such product reduces the complexity of the supplychain and the presentation of the product at retail and online sites.

It will be understood that a shape that matches the wearer's foot can bederived by creating a shape that is customized to an individual's foot.Footbeds commonly known as orthotics have been used in the medicalindustry for some time and are manufactured by taking a custom mold of awearer's foot. While custom orthotics can provide good results incomfort and support, they come with a cost in time and money. Thesedevices require time to take a custom mold of the wearer's foot andoften cost hundreds of dollars to manufacture. Therefore, these devicesare normally reserved for individuals with severe foot health problems.

While the combination of the footbed base 20 and heel plate 30 willprovide the correct geometry for optimal footbed shape, it should beunderstood that someone experienced in the art can create a similaroptimal shape using a different combination of materials. In a secondembodiment of the invention the critical top shape of the footbed 10 canbe produced via molding of PU or EVA foams or similar polymers. Oneschooled in the art can use compression molding, injection molding, oropen pour molding combined with the correct polymers to mold a footbed10 into the optimal shape that will provide comfort, cushioning andsupport that take into account parameters such as heel cup depth, heelcup diameter, medial heel wall angle, lateral heel wall angle, rear heelwall angle, medial heel wall height, lateral heel wall height, rear heelwall height, arch height, and arch spring.

Measurements: Table 1 shows a measurement profile for a footbed 10 thatprovides optimal comfort and support. It should be understood that smallvariations from each of the below measurements can be allowed and stillachieve the desired results. The measurements below describe a footbedof a US size 9. Certain important measurements are prefaced with anasterisk.

TABLE 1 Footbed Measurement Profile millimeters Footbed Length 296Forefoot Width 102 *Heel Width 70.5 *Heel Plate Length 176.5 *Heel PlateWidth at Heel 67.0 *Heel Plate width at arch 67.7 Forefoot Thickness 5.0*Heel Cup Lateral Wall Height 14.5 *Heel Cup Medial Wall Height 16.4*Heel Cup Rear Wall Height 15.5 *Heel Cup Depth 15.0 *Heel Cup LateralWall Angle 43.3 *Heel Cup Medial Wall Angle 43.9 *Heel Cup Rear WallAngle 42.7 *Arch Height 15.8 *Arch Spring from Lasting Board 4.9

As noted, the above measurements are for a footbed 10 designed to beused with a size 9 shoe. It should be understood that one experienced inthe art may adapt the dimensions to different footbed sizes based onindustry standard size grading and the instant algorithms.

To produce a certain profile for a shoe size, the process may beginthrough data collection. In the data collection process subjects havetheir feet scanned using a 3D scanner. Each subject's foot is placed ina neutral position by palpating the subtalar joint (STJ) to ensure theneutral position. Scanned files may be divided into subsets based on thesubject's shoe size.

One-dimensional measurements may also be extracted from the scans andpatients were categorized as according to gender and activity level.Heel to ball length and foot breadth were examined to determine if adifference existed between athletes and non-athletes. A One-Way AnovaAnalysis was conducted to assess differences between independentvariables on a single dependent variable after controlling for theeffects of one or more covariates. For example, in one analysis, meanarch height was compared by foot type and activity level. The controlvariables were heel to ball length and foot breadth, chosen specificallybecause of their known effects on the dependent variable.

Scanned files may then be aligned based on correspondence paired points.These points are anatomical and include the seven key or“representative” anatomical points outlined below. This ensures that allfiles are anatomically aligned.

From the scanned files, a 3D contour is extracted, the 3D contour issmoothed by processing it via a filter, such as, for example, a Poissonfilter. A smooth mesh remains of the 3D foot scan of the sole of thefoot. That data is then processed and analyzed based on heel to balllength and foot breadth to determine the shape and form factor of theorthotic insert.

In some examples, statistical analysis may be performed on the data,such as for example, an F-test. The F-test of significance will be usedto assess the main and interaction effects. F is the between-groupsvariance (mean square) divided by the within-groups variance (meansquare). When the F value is greater than 1, more variation occursbetween groups than within groups. When this occurs, the computedp-value is small and a significant relationship exists. If significanceis found, comparison of the original and adjusted group means canprovide information about the role of the covariates. Becausepredictable variances known to be associated with the dependent variableare removed from the error term, ANCOVA increases the power of theF-test for the main effect or interaction. Essentially, it removes theundesirable variance in the dependent variable. The assumptions ofnormality and homogeneity of variance was assessed. Normality assumesthat the scores are normally distributed (symmetrical bell shaped) andwill be assessed using the one sample Kolmogorov Smirnov (KS) test.Homogeneity of variance assumes that both groups have equal errorvariances and will be assessed using Levene's test. If the assumption ofnormality is violated (skewed bell shaped), the p-value will be assessedwith the Kruskal-Wallis H Test.

Seven key anatomical measurements are derived from the smoothed 3Dcontour. The seven key anatomical measurements are described below andinclude:

1^(st) Metatarsal Excursion (or heel-to-head of first metatarsalphalangeal joint): This is the length from the back of the heel to thecenter of the 1^(st) metatarsal phalangeal joint (1^(st) MPJ) as shownin FIG. 3A.

5^(th) Metatarsal Excursion (or heel-to-head of fifth metatarsalphalangeal joint): This is the length from the back of the heel to thecenter of the 5th metatarsal phalangeal joint (5^(th) MPJ) as shown inFIG. 3A.

Heel Width: The width of the heel at its widest point as shown in FIG.3B.

Forefoot Width: The width at the widest point of the forefoot; typicallythe distance from the medial side of the 1^(st) MP joint to the lateralside of the 5^(th) MP joint as shown in FIG. 3C. Additionally, theforefoot width measurement is helpful in determining if the appliedfootwear has adequate room to accommodate the function and tissueexpansion of the forefoot.

Arch Height: Height of the medial arch at its tallest point as shown inFIG. 3D. The medial arch absorbs and redistributes forces from themuscles in the leg and the ground back to the foot and body so that weare able to move fluently. The height of the arch can give us an idea ofhow well forces are generated and absorbed and reabsorbed. Just like thecalcaneus there are thought to be several factors that influence archheight.

Arch Length: Length of the medial arch from where it starts close to theheel and proceeds distally to a point just proximal to the 1^(st) MPJ inthe forefoot as shown in FIG. 3D.

Foot Length: Length of the foot as measured from the back of the heel tothe longest toe as shown in FIG. 3E. Typically the 1^(st) or 2^(nd) toe.This measurement gives us a ratio value of overall foot size,considering width, girth and length measurements of the arches thatsupport the foot.

In some examples, these seven representative measurements are used tocreate a contoured shape insert with superior fit. Two measurements, inparticular, produce an insert that is superior to others known in theart. Specifically, the first metatarsal length measurement and the fifthmetatarsal length are not commonly used because there is too muchvariability in the lengths of these bones. Instead, research supportingthe current disclosure has discovered that the variability of thoseparticular bones has a lot to do with anthropometrics that is notconsidered during footwear measuring. Therefore, the algorithm andstructural design of the insert normalizes and define the shape based onthe variability of those two bones, which creates an insert thatprovides the best fit for virtually every foot and is taken from acalculation based on variations of those two specific parts of the footin addition to the other measurements.

EXAMPLE 1

In one example, the algorithm may be understood as having two steps. Ina first step, the algorithm outlines how to fit footbed parameters intothe average foot size standard parameters. In the second step, thealgorithm will match different insoles with their approximate insole or(last bottom) parameters.

The footbeds described herein are configured specifically to providebest fit for any foot size inside any shoe. The methods employed viasoftware help the user validate the values assigned to the size ofspecific footwear features as follows:

Step 1 Overview

A software having a method for foot sizing is contemplated which takesin certain variables that describe different parts of the foot. Thesevariables may include the forefoot width, rear foot width, first raylength, fifth ray length and foot size. The software program outputs tothe screen information regarding each of the foot parameters inputted bythe user. Specifically, the program tells the user whether the input iswithin the range of measurement values for that specific foot parameter.For example, if the value is within the range, the output will display amessage saying, “The output was valid.” If the value is outside of therange, the message will say “Number is invalid” and also display theinteger value needed to add or subtract from the input value to make thevalue within the range of valid values.

Independent and Dependent Variables

The algorithm utilizes independent and dependent variables in the dataanalysis. The independent variables may include forefoot width, rearfootwidth, first ray length, fifth ray length and foot size. Alternatively,dependent variables are the selected dimensions of the insole lastbottom blue print which will determine footbed dimension modifications.

Step 2 Logistic Regression Analysis

In some examples, six best-fit points were computed from point clouds ofthe foot scan raw data, the six best-fit points including forefootwidth, rearfoot width, arch height, arch length, heel-to-head of firstmetatarsal phalangeal joint, and heel-to-head of fifth metatarsalphalangeal joint. The aforementioned F-test of significance was used asthe statistical test to assess the main and interaction effects anddetermine the six best-fit points of the instant footbed. A decisiontree learning algorithm was then used to predict the dependent variablesfor each foot size from the data (i.e., forefoot width, rearfoot width,arch height, arch length, heel-to-head of first metatarsal phalangealjoint, heel-to-head of fifth metatarsal phalangeal joint). Thisframework may be used to predict multivariate data includingnonparametric regressions in which the predictor does not take apredetermined form but is constructed according to information derivedfrom the data. Nonparametric regression requires larger sample sizesbecause the data must supply the model structure as well as the modelestimates. In some examples, a nonparametric multiplicative regression(NPMR) is used, which is a form of nonparametric regression based onmultiplicative kernel estimation. Like other regression methods, thegoal is to estimate a response (dependent variable) based on one or morepredictors (independent variables).

NPMR algorithms may enable the software to model automatically thecomplex interactions among predictors. The unknown parameters, denotedas {β} beta which may represent a scalar or a vector.

The independent variables, {X}, X.The dependent variable, {Y}, Y.A regression model relates Y to a function of X and {β} beta. y≈f(x,β)

The approximation of the points will be formalized in a algebraicequation as E (y|x)=f(x,β).

The regression analysis is carried out by knowing the form of thefunction f, the form of this function is based on knowledge about therelationship between Y and X and does not rely on the data, therefore fmust be specified or a convenient form for f will be chosen. Resultingdata will estimate a unique value for R beta that best fits the data insome sense, and the regression model when applied to the data can beviewed as an over determined system or a system of equations. A sampleof a regression analysis is shown in FIG. 4.

Computation

In the instant method, the shape of the response surface may be unknown.The predictors are likely to interact in producing the response; inother words, the shape of the response to one predictor is likely todepend on other predictors. The response is either a quantitative orbinary variable that can be cross-validated and applied in a predictiveway to the standard deviations of each of the 6 best-fit points. Oneexample of a regression model is shown in FIG. 5. Additionally, computersimulation may also be used to simulate the outcomes of a mathematicalmodel associated with said system, said simulations being used to checkthe reliability of a chosen mathematical model. On possible example ofpseudo-code for predicting certain measurements to foot length is shownbelow:

If foot_length==6 then:

-   -   First_ray=3.5    -   Fifth_ray=2.9    -   Foot_arc=2.4    -   Rear_foot_width=3.1    -   Forefoot_width=3.08

else if foot_length==7 then:

-   -   First_ray=3.4    -   Fifth_ray=2.3    -   Foot_arc=2.2    -   Rear_foot_width=2.8    -   Forefoot_width=3.21

else if foot_length==8 then:

-   -   First_ray=3.7    -   Fifth_ray=2.6    -   Foot_arc=2.4    -   Rear_foot_width=3.0    -   Forefoot_width=3.3

EXAMPLE 2

The previous techniques and methods may be incorporated into a singlemethod for manufacturing a footbed as shown in FIG. 6, and withreference to Tables 1-3 below.

A method of manufacturing a footbed may include acquiring data fromthousands of foot scans and storing them in a database, each of the footscans including requesting that the patient place their foot in asub-talar neutral position prior to scanning (602). The data may besmoothed and filtered based on the average of 1000s of scans that aresorted by shoe size (604). In some examples, the sorting by shoe size isdone by creating different groupings of data, each bucket representing aspecific shoe size including half-sizes. That is, grouping may becreated for size 8, 8.5, 9, 9.5, 10, 10.5, 11, etc. A multivariatelinear regression model is created using the techniques discussed above(606). For each of the key foot measurements, differential coefficientsare determined (608), and measurements are calculated for each key footparameter per Table 2 and the formulas below using the differentialcoefficients:

TABLE 1 Foot Anthropometric Dimensions Measurement Definition L_(HW)Heel Width L_(1MH) Heel to 1^(st) Met Head L_(5MH) Heel to 5^(th) MetHead L_(FFW) Forefoot Width L_(AL) Arch Length L_(AH) Arch Height

TABLE 2 Footbed Dimensions Measurement Definition M_(HW) Footbed HeelWidth M_(1MH) Heel to 1^(st) Met Head M_(5MH) Heel to 5^(th) Met HeadM_(FFW) Forefoot Width M_(AL) Arch Length M_(AH) Arch Height

TABLE 3 Differential Ratio Differential Ratio Definition D_(HW) FootbedHeel Width D_(1MH) Heel to 1^(st) Met Head D_(5MH) Heel to 5^(th) MetHead D_(FFW) Forefoot Width D_(AL) Arch Length D_(AH) Arch Height

Formula #1:

Determine foot anthropometric measurement if footbed parameters areknown:

L=M+[D·N]

Formula #2:

Determine footbed parameters if anthropometric parameters are known:

M=L−[D·N]

Where:

-   -   L=Known Value for anthropometric measurement;    -   M=Known Value from existing footbed;    -   D=Differential ratio derived from regressed data for each half        size;    -   N=whole number representing the number of increments in shoe        size greater than size 6; and:

Thus, each footbed/anthropometric dimension can be determined bycalculating the dimension for each of the critical footbed measurementincorporating the parameters for each item listed in Tables 1 and 2(above), and incorporating the differential coefficient for each keyparameter via the product differential ratio “D” and a whole number “N”(614). The result is a footbed model that is almost ready formanufacturing with some adjustments made to ensure proper fitment into ashoe.

A second set of data may be acquired relating to footwear last bottomperimeter from a given shoe (620). The last bottom data may be convertedto vector/scalar coordinates (622). As shown in step 620, footbeddimensions from step 614 may be compared to the last bottom perimeterfrom step 622 to ensure that the footbed will properly fit into the shoe(630). If no adjustments are necessary, a final footbed shape isproduced (640). If, however, it is determined that the footbed dimensionfrom step 614 will not fit within last bottom perimeter, then thefootbed model may be modified to ensure proper fit (e.g., within onestandard deviation). In some examples, a footbed dimension that will notfit within a last bottom perimeter may require additional adjustment(e.g., addition or subtraction) from the footbed dimension.

According to the present disclosure, the footbed has two primarycomponents: (1) the top portion constructed of foam there to providecushioning, shock absorption, comfort, and pressure distribution, and(2) the bottom portion constructed of a material firmer than the topportion and there to provide shape, support, stability, and pressuredistribution. The bottom portion does not extend to the same length asthe top portion.

In order to achieve manufacturing efficiencies, the bottom portion,which is typically molded and therefore more expensive, scalesdifferently than the top portion. There are fewer sizes of the bottomportion. Typically, two sizes of the top portion are used with one sizeof the bottom portion and, therefore, fewer molds are needed to producea complete set of sizes for the footbed. For example, footbed size items9 & 9.5 would use a one size of the bottom portion combined with twosizes of the upper portion. In certain examples, care is taken to ensurethat the firmer bottom portion is aligned/graded according to the foot'sanatomy so that negative effects do not occur. To ensure proper fitment,(a) the distal edge of the of the bottom portion is always at least ½inch proximal to the MP Joints, (b) the width of the proximal end of thebottom portion is ½ the distance from the 1st MPJ to the 5th MPJ, and(c) the width of the bottom portion at the widest part of the heel is ⅛″wider than the heel (anatomical heel).

The shape and stiffness of the arch is important for comfort, support,and stable control of the foot. To accommodate personal preferences ofcomfort in the arch, 3 levels of stiffness are provided for the footbedinstead of formulating a different arch shape for each patient. Thisprovides 3 levels of arch stiffness per size to accommodate differentarch dynamics and personal preference.

In some examples, the flexural modulus (the ratio of flex stress andflex strain) of the footbed, determined via 3-point bending tests may bevaried. The flexural modulus may be calculated according to thefollowing equation:

E=(L{circumflex over ( )}3*F)/(4*b*h{circumflex over ( )}*y)

where:

-   -   E=flexural modulus    -   L=Span length of test specimen    -   F=Load    -   b=width of test specimen    -   h=thickness of test specimen    -   y=displacement

In at least some examples, a first footbed may be formed of a firstflexural modulus, a second footbed may be formed of a second flexuralmodulus that is approximately half of the first flexural modulus, and athird flexural modulus may be formed of a third flexural modulus that isapproximately half of the second flexural modulus. For example, threefootbeds of generally the same shape and size may be formed as follows:

Stiffest with a flexural modulus of 1094

Medium with a flexural modulus of 525

Least stiff with a flexural modulus of 229

The present disclosure also contemplates a unique shape for the heelcutout. This cutout allows the top portion of the footbed, typicallysofter, shock absorbing material, to protrude through the stiffermaterial in the bottom portion and provides some benefits. The shape ofthe cutout in the heel is unique and derived by examining criticalanatomical points on the heel bone (calcaneus). The posterior portion ofthe calcaneus has condyles/tuberosities. A condyle or tuberosity is aportion of a bone where ligaments and tendons can attach to the bone andis typically a small projection of the bone that gives the tendon orligament a place to attached on to, as opposed to a perfectly smoothbone portion that would make attachment more difficult.

The tuberosity/condyle projections on the posterior surface of the heelare connection points for a number of connective tissues with theplantar fascia being one of the primary connections. The cutout, shapedas a guitar pick, provides additional cushioning and shock absorption atthe calcaneal tuberosity. This connection point is often the site ofinflammation of the plantar fascia, commonly known as plantar fasciitis,which causes pain and soreness and affects many individuals.

The shape of the guitar pick cutout is configured and arranged toprovide cushioning and shock absorption at critical anatomical points toguard against plantar fasciitis due to prolonged trauma in the heel, butdoes not reduce the support and control at the heel that is provided bythe firmer bottom portion of the footbed.

Providing a larger cutout with softer material projecting through thebottom portion of the footbed might guard against heel trauma, but maycome at a cost of reduced stability and control at the heel. The ideal“guitar pick” shape provides the needed cushioning and shock absorptionwithout loss of stability and control.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

What is claimed is:
 1. A method of manufacturing a foot insertcomprising: positioning each patient's foot in a neutral position;collecting three-dimensional data of at least one foot of each patientand placing the scan in a collection of scans representing a samplepatient population; separating the collection of scans into groupingsbased on each patient's preferred shoe size; aligning the scans withineach grouping; obtaining at least one representative measurement foreach grouping; and modeling an insole based on the at least onerepresentative measurement and determining a footbed dimension from ananthropometric dimension and a differential coefficient for at least oneshoe size.
 2. The method of claim 1, further comprising the step ofcreating a multivariate linear regression model.
 3. The method of claim2, further comprising the step of training the model based on at least500 samples of the data.
 4. The method of claim 3, further comprisingthe step of testing the accuracy of the model.
 5. A method ofmanufacturing a foot insert comprising: positioning each patient's footin a neutral position; collecting three-dimensional data of at least onefoot of each patient and placing the scan in a collection of scansrepresenting a sample patient population; separating the collection ofscans into groupings based on each patient's preferred shoe size;aligning the scans within each grouping; obtaining at least onerepresentative measurement for each grouping; modeling an insole basedon the at least one representative measurement; and using anonparametric multiplicative regression to estimate the at least onerepresentative measurement.
 6. The method of claim 5, wherein estimatingthe at least one representative measurement includes estimating at leastone of the forefoot width, the rearfoot width, the arch height, the archlength, the heel-to-head of first metatarsal phalangeal joint, and theheel-to-head of fifth metatarsal phalangeal joint.
 7. The method ofclaim 6, wherein estimating the at least one representative measurementincludes estimating each of the forefoot width, the rearfoot width, thearch height, the arch length, the heel-to-head of first metatarsalphalangeal joint, and the heel-to-head of fifth metatarsal phalangealjoint.
 8. A method of manufacturing a foot insert comprising:positioning each patient's foot in a neutral position; collectingthree-dimensional data of at least one foot of each patient and placingthe scan in a collection of scans representing a sample patientpopulation; separating the collection of scans into groupings based oneach patient's preferred shoe size; aligning the scans within eachgrouping; obtaining at least one representative measurement for eachgrouping; modeling an insole based on the at least one representativemeasurement; and adjusting the insole based on acquired data fromfootwear.
 9. The method of claim 8, wherein adjusting the insole basedon acquired data from footwear includes adjusting the insole based on afootwear last bottom perimeter.
 10. The method of claim 9, furthercomprising the step of converting last bottom data to vector and scalarcoordinates and comparing the vector and scalar coordinates to themodeled insole.